2016-10-28 14:18:57

Today's Topics

  • Cognition

The emergence of behavior

Cambrian Explosion

What sparked the explosion? (Fox 2016)

  • Behavior requires energy
  • Behavior requires perception at a distance
  • Behavior requires action

What behaviors are essential for animals to perform?

  • Ingestion
  • Defense
  • Reproduction

What behaviors are essential for animals to perform

  • Perception at a distance
  • Locomotion
  • Object manipulation/consumption
  • Signaling/communication

How is the nervous system organized to contribute to these behaviors?

Cajal

Swanson/Cajal Four Systems

Hierarchy of control

Functional segregation

Do what, where, how?

Facets of cognition

  • Perception
  • Attention
  • Imagery

Facets of cognition

  • Learning and conditioning
  • Memory
    • Episodic
    • Semantic
    • Procedural
  • Language
  • Problem-solving

Facets of cognition

  • Thinking
  • Problem solving
  • Decision making
  • Motivation

Cognition and the cerebral cortex

Cortical schema

  • Areas
    • Unimodal sensory
    • Polymodal association
    • Motor
  • Connections
    • Association
    • Commissural

Cortical areas

Cortical schema

  • Columnar structure
  • Cytoarchitectonic differerences (e.g. Brodmann)

Cortical columns

Cortical layers

Cortical connections by layer

  • I:
  • II: Efferent: Ipsilateral association
    • Large pyramidal cells
  • III: Efferent: Contralateral commissural
  • IV: Afferent: Thalamus
    • Small stellate, granule
    • Sub-layers in V1

Cortical connections by layer

  • V: Efferent: Basal ganglia, brainstem, spinal cord: Pyramidal cells
    • Superficial -> Striatum
    • Deep -> Brainstem, spinal cord
  • VI: Efferent: Thalamus

Cortical circuit schematic

Behavioral control column

Behavioral control column

Behavioral control column

Behavioral control column

Behavioral control column

Processing networks

Processing networks

Processing networks

Processing networks

Representing information in a network

Memory capacity of the human brain?

What is learning? What is memory

  • Learning
  • Memory

Biological bases of L&M

  • Changes in patterns of neural activity
  • Changes in connectivity
    • New synapses
    • Altered synapses (strengthened or weakened)

Donald Hebb's Insight

When an axon of cell A is near enough to excite cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A’s efficacy, as on of the cells firing B, is increased. (Hebb, 1949, p. 62)

Neurons that fire together wire together. (Lowell & Singer, 1992, p. 211).

NMDA receptor and 'Hebbian' learning

  • Coincidence detector
    • Sending cell has released NT
    • Receiving cell is/has been recently active
  • Chemically-gated
    • Ligand- (glutamate/aspartate + glycine) gated
  • Voltage-gated
    • Zn++ or Mg++ ion 'plug' removed under depolarization
    • Na+ & Ca++ influx; K+ outflux

NMDA receptor figure

NMDA clinical significance

  • Memantine blocks (Alzheimer's Disease)
  • Implicated in effects of PCP (~schizophrenia: Glu hypothesis)
  • Alcohol, ketamine, nitrous oxide (NO)

Spike-timing-dependent plasticity

Spike-timing-dependent plasticity

Dimensions of stored info

  • Memory of what?
    • Facts/events/places vs. skills
  • Memory of when?
    • Immediate vs. distant past
  • Memory for how long?
    • Seconds vs. years

Memory systems in the brain

Hippocampus

Hippocampus roles

  • Formation, storage, consolidation of long-term episodic or declarative memories
  • Spatial navigation
    • Place cells
    • Grid cells
    • Head-direction cells

Spatial precision of place cells

Human analogue – (Maguire et al. 2000)

(Maguire et al. 2000)

(Maguire et al. 2000)

Hippocampal volume in food-caching birds

Summary

  • Cognition
    • Do what, where, and how
  • The "cognitive" cortex
  • Processing networks
    • Functional specialization
  • Learning and memory
    • Distributed systems
    • Associative learning, NMDA receptors, and the hippocampus

References

Bressler, Steven L, and Vinod Menon. 2010. “Large-Scale Brain Networks in Cognition: Emerging Methods and Principles.” Trends in Cognitive Sciences 14 (6). Elsevier: 277–90. doi:10.1016/j.tics.2010.04.004.

Caporale, Natalia, and Yang Dan. 2008. “Spike Timing-Dependent Plasticity: A Hebbian Learning Rule.” Annu. Rev. Neurosci. 31. Annual Reviews: 25–46. doi:10.1146/annurev.neuro.31.060407.125639.

Fox, Douglas. 2016. “What Sparked the Cambrian Explosion?” Nature 530 (7590): 268–70. doi:10.1038/530268a.

Kjelstrup, Kirsten Brun, Trygve Solstad, Vegard Heimly Brun, Torkel Hafting, Stefan Leutgeb, Menno P. Witter, Edvard I. Moser, and May-Britt Moser. 2008. “Finite Scale of Spatial Representation in the Hippocampus.” Science 321 (5885): 140–43. doi:10.1126/science.1157086.

Maguire, Eleanor A, David G Gadian, Ingrid S Johnsrude, Catriona D Good, John Ashburner, Richard SJ Frackowiak, and Christopher D Frith. 2000. “Navigation-Related Structural Change in the Hippocampi of Taxi Drivers.” Proceedings of the National Academy of Sciences 97 (8). National Acad Sciences: 4398–4403. doi:10.1073/pnas.070039597.

Sherry, David F., Anthony L. Vaccarino, Karen Buckenham, and Rachel S. Herz. 1989. “The Hippocampal Complex of Food-Storing Birds.” Brain, Behavior and Evolution 34 (5): 308–17. doi:10.1159/000116516.

Squire, Larry R. 2004. “Memory Systems of the Brain: A Brief History and Current Perspective.” Neurobiology of Learning and Memory, Multiple Memory Systems, 82 (3): 171–77. doi:10.1016/j.nlm.2004.06.005.

Swanson, Larry W. 2005. “Anatomy of the Soul as Reflected in the Cerebral Hemispheres: Neural Circuits Underlying Voluntary Control of Basic Motivated Behaviors.” Journal of Comparative Neurology 493 (1). Wiley Online Library: 122–31. doi:10.1002/cne.20733.

———. 2012. Brain Architecture: Understanding the Basic Plan. Oxford University Press.